Discussions in Canvas are similar to discussion forums in Chalk or elsewhere on the Internet: one person posts a question or some content, and others respond to that original post or to other responses. These can become assignments if they are graded and given a due date, or they can just be for general discussion.

One important improvement in Canvas is the ability to record or upload audio or video into discussion threads. This enables instructors to create asynchronous speaking practice and assignments. For example, the instructor can post a recorded question and have students record responses, or have students read a passage or watch a video and record their response. This allows the instructor to view students' production multiple times and record spoken feedback, and creates a portfolio for students to view their progress over the course of the quarter/year.

Here is a page from Rutgers with tips and resources about grading threaded discussions.

For more on Discussions, visit the Canvas team's FAQs or videos on Discussions Overview and Discussion Creation, or talk to Nick. He is very excited about this function.